It is to the body alone that we should attribute everything that can be observed in us to oppose our reason.

Doubt is the origin of wisdom

If you would be a real seeker after truth, it is necessary that at least once in your life you doubt, as far as possible, all things.

And as it is the most generous souls who have most gratitude, it is those who have most pride, and who are most base and infirm, who most allow themselves to be carried away by anger and hatred.

The greatest minds are capable of the greatest vices as well as of the greatest virtues.

By 'God', I understand, a substance which is infinite, independent, supremely intelligent, supremely powerful, and which created both myself and everything else [...] that exists. All these attributes are such that, the more carefully I concentrate on them, the less possible it seems that they could have originated from me alone. So, from what has been said it must be concluded that God necessarily exists.

So far, I have been a spectator in this theater which is the world, but I am now about to mount the stage, and I come forward masked.